基于“物质结构与性质”模块再探必修知识——以“电负性”再探“化学键”为例

在 2017 年颁布新《课标》与 2019 年发行新教材的大背景之下,“物质结构与性质”模块的学习得到一定的重视。基于“物质结构与性质”模块再探必修知识,能够打破因为教材编写所导致的模块之间的“独立性”,能够让学生学以致用,深刻体会“结构决定性质”的化学思想。利用“电负性”的相关知识对“化学键”的知识进行补充说明,使知识更有连贯性和整体性。

“化学键”积件的设计与研制

随着计算机辅助教学的发展 ,传统的课件已显示其不足 ,本文介绍一新的教学软件———积件的设计与实现过程。积件素材丰富 ,资料呈现形式多样 ,操作方便 ,且利用积件用户可以方便生成课件。

“无机化学”中“化学键与分子结构”一章的教学探讨

针对“无机化学”课程特点和新生的实际情况,从“力”与“形”两个方面对“无机化学”中“化学键与分子结构”一章的教学难点进行了深层次的梳理与辨析。运用一图十表对知识的难点和重点进行归纳、对比和总结,帮助学生更有效地掌握教学知识。

Structural,mechanical and electronic properties of precipitates in Mg−Zn alloys

To accelerate the development and design of magnesium(Mg)alloys,the structural and mechanical properties of important precipitates in Mg−Zn alloys were studied by experiments and density functional theory.The nano-indentation tests revealed that the hardness of the precipitates initially increased and then decreased with increasing Zn content,and was significantly higher than that of pure Mg and Zn.The calculation results revealed that the precipitates stability initially increased and then decreased with increasing Zn concentration.The bulk moduli of the precipitates increased,whereas their shear and Young’s moduli initially increased and then decreased with increasing Zn content.The decreasing order of ductility for these compounds is MgZn_(2)>Mg_(21)Zn_(25)>Mg_(2)Zn_(11)>Mg_(4)Zn_(7).The surface profiles of the compounds revealed that they are obvious anisotropy.Both the degree of covalency and bond length of covalent bonds initially increased and then decreased with increasing Zn content.

Engineering the coordination structure of Cu for enhanced photocatalytic production of C_(1) chemicals from glucose

Photocatalytic decomposition of sugars is a promising way of providing H_(2),CO,and HCOOH as sus-tainable energy vectors.However,the production of C_(1) chemicals requires the cleavage of robust C−C bonds in sugars with concurrent production of H_(2),which remains challenging.Here,the photo-catalytic activity for glucose decomposition to HCOOH,CO(C_(1) chemicals),and H_(2) on Cu/TiO_(2)was enhanced by nitrogen doping.Owing to nitrogen doping,atomically dispersed and stable Cu sites resistant to light irradiation are formed on Cu/TiO_(2).The electronic interaction between Cu and nitrogen ions originates valence band structure and defect levels composed of N 2p orbit,distinct from undoped Cu/TiO_(2).Therefore,the lifetime of charge carriers is prolonged,resulting in the pro-duction of C_(1) chemicals and H_(2) with productivities 1.7 and 2.1 folds that of Cu/TiO_(2).This work pro-vides a strategy to design coordinatively stable Cu ions for photocatalytic biomass conversion.

First principles calculation on ternary stannide phase narrow band gap semiconductor Na_2MgSn

The electronic structures,chemical bonding,elastic and optical properties of the ternary stannide phase Na2MgSn were investigated by using density-fimctional theory（DFT） within generalized gradient approximation（GGA）.The calculated energy band structures show that Na2MgSn is an indirect semiconductor material with a narrow band gap 0.126 eV.The density of state（DOS）and the partial density of state（PDOS） calculations show that the DOS near the Fermi level is mainly from the Na 2p,Mg 3p and Sn5 p states.Population analysis suggests that there are strongly bonded Mg-Sn honeycomb layers in Na2MgSn.Basic physical properties,such as lattice constant,bulk modulus,shear modulus,elastic constants c（ij） were calculated.The elastic modulus E and Poisson ratio v were also predicted.The results show that Na2MgSn is mechanically stable soft material and behaves in a brittle manner.Detailed analysis of all optical functions reveals that Na2MgSn is a better dielectric material,and reflectivity spectra show that Na2MgSn promise as good coating materials in the energy regions 6.24-10.49 eV.

First principles study of electronic structure, chemical bonding and elastic properties of BiOCuS

The electronic structures, chemical bonding and elastic properties of the tetragonal phase BiOCuS were investigated by using density-functional theory （DFT） within generalized gradient approximation （GGA）. The calculated energy band structures show that the tetragonal phase BiOCuS is an indirect semiconductor with the calculated band gap of about 0.503 eV. The density of states （DOS） and the partial density of states （PDOS） calculations show that the DOS near the Fermi level is mainly from the Cu-3d state. Population analysis suggests that the chemical bonding in BiOCuS has predominantly ionic character with mixed covalent-ionic character. Basic physical properties, such as lattice constant, bulk modulus, shear modulus, elastic constants, were calculated. The elastic modulus and Poisson ratio were also predicted. The results show that tetragonal phase BiOCuS is mechanically stable and behaves in a ductile manner.

First principles calculation of electronic structure, chemical bonding and elastic properties of ultra-incompressible Re_2P

The electronic structures, chemical bonding and elastic properties of the Co2P-type structure phase ultra-incompressible Re2P （orthorhombic phase） were investigated by density-functional theory （DFT） within generalized gradient approximation （GGA）. The calculated energy band structures show that the orthorhombic structure phase Re2P is metallic material. The density of state （DOS） and the partial density of state （PDOS） calculations show that the DOS near the Fermi level is mainly from the Re-5d state. Population analysis suggests that the chemical bonding in Re2P has predominantly covalent character with mixed covalent-ionic character. Basic physical properties, such as lattice constant, bulk modulus, shear modulus, and elastic constants Cij, were calculated. The elastic modulus and Poisson ratio were also predicted. The results show that the Co2P-type structure phase Re2P is mechanically stable and behaves in a brittle manner.

Infrared Spectra and Theoretical Calculations of BS2 and BS2-： Strong Pseudo Jahn-Teller Effect

Laser ablated boron atoms have been reacted with hydrogen sulfide and the reaction products condensed with argon at 4 K, which gave BS2, BS2-, HSBS, and HBS molecules. Reagent isotopic substitution （H2S, H234S, D2S, 10 B, 11B） and variation of boron and hydrogen sulfide concentrations have been used to identify the major products. Both BS2-- and BS2 were identified as linear molecules with no significant difference in the structure parameters, but the B-S anti-symmetric stretching vibration of BS2 is significantly lower than that of BS2-, which is ascribed to pseudo Jahn-Teller effect. Theoretical calculation was employed to have an insight into the interaction nature of the bonds in the corresponding products.

Chemical bonding and elastic properties of quaternary arsenide oxides YZnAsO and LaZnAsO investigated by first principles

The structural parameters, chemical bonding and elastic properties of the tetragonal phase quaternary arsenide oxides YZnAsO and LaZnAsO were investigated by using density-functional theory （DFT） within generalized gradient approximation （GGA）. The GGA calculated structural parameters are in agreement with the experimental results. Population analysis suggests that the chemical bonding in YZnAsO and LaZnAsO can be classified as a mixture of ionic and covalent characteristic. Single-crystal elastic constants were calculated and the polycrystalline elastic modules were estimated according to Voigt, Reuss and Hill＇s approximations （VRH）. The result shows that both YZnAsO and LaZnAsO are relatively soft materials exhibiting ductile behavior. The calculated polycrystalline elastic anisotropy result shows that LaZnAsO is more anisotropy in compressibility and YZnAsO is more anisotropy in shear.

A Colorimetric Receptor Based on SchiffoBase Bearing Azo-Phenolic Hydroxy Group

A novel N-（2-hydroxy-5-chlorodibenzophenone）-N＇-[2-hydroxy-5-azophenyl-benzaldehyde]- 1,2-diaminobenzene receptor has been synthesized by simple steps with good yields. The anion recognition properties were studied by ultraviolet-visible spectroscopy. The results showed that the receptor had a higher affinity to F-, AcO-, and H2PO4-, but no evident binding with Cl-, Br-, and l-. Upon addition of the three former anions to the receptors in DMSO, the solution exhibited an obvious color change from colorless to yellow, which could be observed by the naked eye, thus the receptor could act as a fluoride ion sensor even in the presence of other halide ions. The UV-Vis data indicates that a 1：1 stoichiometric complex is formed through hydrogen bonding interactions between receptor and anions.

Analysis of Single-Walled Carbon Nanotubes Using a Chemical Bond Element Model

A three dimensional nano-scale finite element model （FEM）, called the chemical bond element model, is proposed for the simulation of mechanical properties of single-walled carbon nanotubes （SWCNTs） based upon molecular mechanics method. Chemical bonds between carbon atoms are modeled by chemical bond elements. The constants of a sub-stiffness matrix are determined by using a linkage between molecular mechanics and continuum mechanics. In order to evaluate the correctness and performance of the proposed model, simulation was done to determine the influence of nanotube wall thickness, radius and length on the elastic modulus （Young＇s modulus and shear modulus） of SWCNTs. The simulation results show that the choice of wall thickness significantly affects the Young＇s modulus and shear modulus. The force field constants is also very important, because the elastic modulus is sensitive to force field constants and the elastic properties of SWCNT are related to the radii of the tubes. The contribution of length to elastic modulus is insignificant and can be ignored. In comparison with the Young＇s modulus and shear modulus reported in the literature, the presented results agree very well with the corresponding theoretical results and many experimental measurements. Furthermore, if the force constants are properly chosen, the present method could be conveniently used to predict the mechanical behavior of other single-walled nanotubes such as boron nitride nanotubes. The results demonstrate the value of the proposed model as a valuable tool in the study of mechanical behaviors of carbon nanotubes and in the analysis of nanotube-based equipments.

Sonication for advanced drinking water treatment

This paper investigated the feasibility of sonication as an advanced treatment method for drinking water production and used comprehensive indexes of water quality to examine its efficiency. Results show that sonication significantly reduces the toxicity of water. Sonication with 5 W/L at 90 kHz lasting for 30 rain decreases the water SUVA and the disinfection byproduct formation potential （DBPFP） by 38.7% and 27. 2% respectively. Sonication also decreases the UV254 by more than 50% through destroying unsaturated chemical bonds. Higher sound intensity and higher frequency benefit the reduction of TOC and UV254. Besides, sonication significantly increases the affinity of organics with granular activated carbon （ GAC ） , and thus the hybrid sonication-GAC method reduces the water TOC, COD, UV254, and DBPFP by 78.3%, 69.4%, 75.7%, and 70.0% respectively. Therefore, sonication and the hybrid sonication-GAC metbod are proposed as advanced treatment methods for drinking water.

Photocatalytic conversion of waste plastics to low carbon number organic products

As a great threat to all livings on earth,waste artificial plastics now are everywhere,from oceans to our cells[1].The world cannot withstand the growing waste plastic in million tonnes every year,which has already caused environmental pollution and economic losses[2].Besides the efforts for preparing novel plastics with the self‐decomposition ability,methods are needed to clear away these waste plastics leftover from history or recycle well this organic carbon resource[3].Photocatalysis is a potential solution for the conversion of waste plastics under mild conditions.In this perspective,we highlight the effect of photocatalytic approaches toward the generation of low carbon number organic products(C_(n) products,n≤8)from waste plastics,which can proceed under an inert or aerobic atmosphere.Notably,critical analysis of the carbon source in products is necessary to reveal the active species for the C–X bonds(X=C,N,and O)cleavage of plastics.Finally,we outline potential avenues for further development of this emerging field to enhance the yield of C_(n)(n≤8)products from waste plastics.

Spectroscopic Analysis of Structural Transformation in Biodiesel Oxidation

The oxidation behavior of three biodiesels of different origins,viz.rapeseed oil derived biodiesel,soybean oil derived biodiesel and waste oil based biodiesel,were tested on an oxidation tester.The chemical compositions of the biodiesels were characterized by gas chromatography.Thereafter,the structural transformation of fatty acid methyl ester(FAME)of the biodiesels was analyzed by an infrared spectrometer and an ultraviolet absorption spectrometer.The results demonstrated that the oxidation behavior of biodiesels of different origins was closely related to the composition and distribution of FAMEs.Higher concentration of unsaturated FAME with multi-double bonds exhibited poorer oxidation resistance.Furthermore,cis-trans isomerization transformation occurred in the unsaturated FAME molecules and conjugated double-bond produced during the oxidation process of biodiesel.Greater cis-trans variations corresponded to deeper oxidation degree.The higher the content of unsaturated FAME with multi-double bonds in a biodiesel,the more the conjugated double bonds was formed.

Chemical Bond Properties and Isomer Shifts of Tl2Ba2Ca2Cu3O10

Tl2Ba2Ca2Cu3O10 was reported to be a superconductor with a highest transition temperature of 125 K among the homologous series of Tl2Ba2Can-1CunO2n＋4. The direct information on the Cu ion site at the atomic level is important for elucidating the superconductivity mechanism. The local bond properties of Tl2Ba2Ca2Cu3O10 were studied using the average band-gap model. The calculated results show that the covalency of Cu（1）-O bond is 0.561, and the average covalency of Cu（2）-O is 0.296. Mossbauer isomer shifts of 57Fe in Tl2Ba2Ca2Cu3O10 were calculated using the chemical surrounding factor, defined by covalency and electronic polarizability. It is verified that for lower doping, Fe substitute the Cu at the Cu （1） site in forms of Fe^3＋ and Fe^4＋; for higher doping, Fe^3＋ and Fe^4＋ ion occupies Cu（1） and Cu（2） site respectively. The studies show that the determination of the correspondence between spectrum components and actual copper sites occupied by MSssbauer nucleus was made easier with the aid of the calculation results of the chemical bond parameters.

Benchmarking the Polyatomic Reaction Dynamics of X+Methane

With recent developments of sophisticated experimental techniques and advanced theoretical methods/computations, the field of chemical dynamics has reached the point that theoryexperiment comparisons can be made at a quantitative level in very fine details for a prototypical A+BC system. As the system becomes larger, more degrees of freedom are involved and the complexity increases exponentially. At the same time, the multifaceted nature of polyatomic systems also opens up the possibilities for observing many new chemistry and novel phenomena|a land of opportunities. For the past 15 years or so my laboratory has delved into the reaction dynamics of methane+X (X: F, Cl, O(3P), and OH). This effort shifts the paradigm in the field of reaction dynamics by making the title reaction a benchmark polyatomic system. In this account, I shall disclose my thinking behind some of the key concepts and methods we introduced and how the unexpectedly discovered phenomena led to other uncharted territories. Those ndings not only enrich our understanding of the specific reactions we studied at the most fundamental level and inspire the theoretical developments, but also shape our thinking and lay the foundation for future explorations of different aspects of the multifaceted nature of polyatomic reactivity.

Study on Infrared Spectra and Chemical Bonding of the Cluster Anion[Cl_2FeS_2MoS_2Cu(PPh_3)_2]￣-

The Fourier transform infrared spectra of the cluster anion[Cl2Fe2S2MoS2Cu(PPh3)2]- are measured between 550 and 90 cm(-1).The empirical assignments have been made for the vibration bands of main valence bonds.In order to verify the assignments of the bands and obtain the force constants the approximate normal coordinate analysis for the title anion has been carried out.It is found that the calculated frequencies are in good agreement with the observed ones.While Quantum-Chemical calculation is used to elucidate the chemical bonding characteristics for the title anion.

First principles calculation on electronic structure,chemical bonding,elastic and optical properties of novel tungsten triboride

The electronic structures,chemical bonding,elastic and optical properties of the novel hP24 phase WB3 were investigated by using density-functional theory(DFT) within generalized gradient approximation(GGA).The calculated energy band structures show that the hP24 phase WB3 is metallic material.The density of state(DOS) and the partial density of state(PDOS) calculations show that the DOS near the Fermi level is mainly from the W 5d and B 2p states.Population analysis suggests that the chemical bonding in hP24-WB3 has predominantly covalent characteristics with mixed covalent-ionic characteristics.Basic physical properties,such as lattice constant,bulk modulus,shear modulus and elastic constants Cij were calculated.The elastic modulus E and Poisson ratio υ were also predicted.The results show that hP24-WB3 phase is mechanically stable and behaves in a brittle manner.Detailed analysis of all optical functions reveals that WB3 is a better dielectric material,and reflectivity spectra show that WB3 can be promised as good coating material in the energy regions of 8.5-11.4 eV and 14.5-15.5 eV.

Research on C—C Bond Length Distribution in Hydrocarbon Molecules

The C--C bond dissociation energy （BDE） is a very important data in research of hydrocarbon cracking reactions, because it reflects the difficulty level of chemical reactions. But it is very difficult to obtain the C--C bond dissociation energy （BDE） by experiments, so using quantum chemistry calculation such as density functional theory （DFT） to study the C--C bond dissociation energy is a very useful means. The impact of acceptor substituents and donor substituents on the C--C bond length distribution was studied.